Thermoelectric properties of MxMo6Te8 （M=Ag, Cu）

Ag and Cu filled Chevrel phase MxMo6Te8 (x=1.0, 2.0) samples were synthesized by direct solid state reaction and spark plasma sintering. The electrical and thermal properties were investigated in the temperature range of 300-800 K. The results show that both the electrical and thermal properties are affected by filler atoms. Although the electrical conductivity of MxMo6Te8 is slightly higher than that of state-of-the-art thermoelectric material, such as filled skutterudites, the absolute value of Seebeck coefficient is relatively low. Due to the phonon scattering by the filler atoms, the decrease of the thermal conductivity and the lattice thermal conductivity is obvious. As a result, the dimensionless figure of merit(ZT) is improved over the whole temperature region. The highest ZT value is 0.034 at 800 K for the AgMo6Te8 sample.     

锗相的存在对Sr_8Ga_(16)Ge_(30)clathrates结构热电材料性能的影响

无机clathrate结构化合物是非常有前景的热电材料.在镓取代的锗基clathrate结构热电材料的合成中,普遍存在锗的第二相.本研究合成了多晶Sr_8Ga_(16)Ge_(30) clathrates 结构热电材料.用X射线衍射结合样品抛光表面的背散射电子像对样品中锗相的含量进行表征.测试可知,材料表现为n型半导体,随着Ge相含量的增大,Seebeck系数绝对值增大,电导和热导率减小.功率因子最大为12.8 μW·K~(-2)cm~(-1).Sr_8Ga_(16)Ge_(30)样品在650 K的最大ZT值达到0.65.